Means for preventing the erosion of guns.



Patented Aug. 20, 1912. V 2 SHBETS-SHBET 1.

, 0 AZWNMVM@ `\\\5 w W -L W i www K A. A.- ACKERMAN. MEANS PoR PRBVENTING THE ERosIoN or GUNS.

APPLICATION FILED DEG. 21, 1911.

Patented Aug. 20, 1912.

2 SHEETS-SHEET 2.

E 50@ o l mi ALBERT AMMERMAN ACKERMAN, 0F THE UNITED STATES NAVY.

MEANS FOR PREVENTING THE EROSION OF GUNS.

Application ledDecember 21, 1911.

lowing to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My present invention relates to improvements in means for preventing the erosion of guns, and it is especially intended. to supply means carried by the shell, which may be used in guns of ordinary construction without necessitating changes in theshape of the bore of the gun, or any of the accessories of the gun proper.

The purpose of this invention is to prevent erosion; restore the efficiency of eroded guns; lubricate the bore in advance of the rotating band; and in general, reduce the wear and tear of high powered guns.

The principle is accepted that erosion is caused by the escape-of powderl gases past the projectile before it has moved from its loaded position. Once started, the rotating band is swaged into the riliing and practically stops the leaks. Before that moving pressure is attained, however, and throughout a large part of the elapsed time between ignition and expulsion, there are lower pressures which, though unable to overcome the inertia of the projectile, givef an intense velocity to the light, nascent gases of early combustion escaping lthrough chamber leaks. Obviously larger, hotter, and chemically more active, volumes of gas escape,'-under greater pressure,- in the case of large calibers and high velocities, than with the reverse.

Corrosion by the hot, but overloaded and almost inert gases following the projectile is practically non-existent. Their velocity, while pushing the shell, especially past the parts of the bore, commonly showing erosion, is intinitesimal compared with that-of the first .gascs freely escaping under .pressure; the late and slow moving gases are reducing rather than oxidizing. Abrasion by them should be greater with the higher velocity attained part-way down the bore than at the projectiles seat. These follow- Specication of Letters Patent.

Patented Aue. 20, 1912. serial Ne. 667,121. i

ing gases too would naturally attack, if they corrode or abrade at all, the salient lands of the riliing rather than the grooves or erosion gutters. nFinally, erosion by following gases and powder fragments, would be distributed with fair uniformity around the bore at the shell seat and beyond, rather than confined to deepening and extending the erosion gutters near the origin of riding.

The rotating band, especially of heavy projectiles, is easily deformed in transportation or handling; the clearance necessary to load puts the shell out of axial alinement Vwith the bore: particles, as powder residuum, are also swept along and jammed between shell and bore in loading., Some or all of these conditions are generally present and produce crevices for the escape'of gases, even in new and uneroded guns.

The lost gases are those which atleet comb ination most readily,-they are in fact, the moving agents of combustion; only through their combination with the `unconsumed powder can they liberate fresh oxidizing material. Should any of these gases escape past the projectile in the early stage of charge combustion, there is a double disastrous eiect:-not only is their nascent avidity exercised in corroding the avenues of escape, instead of extending combustion, but their leakage carries with it heat, pressure and affinity, so that the combustion of the remainder of the charge is retarded or even rendered incomplete. After leakage of this first formed gas, there is left in the chamber an overweight of base as compared with acid in the reaction of explosion. That is,- of part to be dissolved and gasied as to the means for accomplishing the solution. Hence, when the breech is opened immediately after the discharge, and atmospheric oxygen comes in contact with the heated, combustible gases, smothered in the bore, there is or may be a flare-back'.

To summarize :--On ignition of the charge, a volume of super-oxidized gas ows through the crevices between projectile and bore with a velocit-y increasing to many times that of the projectile at the muzzle. This leak continues for at least a large part of the time interval between ignition and movement of the projectile. leak is like the oxidizing fiame of a blowpipe. playingr with great force on certain small areas of the bore. Similar but more minute leaks, past the breech gas-check disks,

In -effect thisv have been greased patches, wads, sabots,

lexpanding rings,`and so-called mechanical lits. As a rule, the more eliicient the device was for low pressures, the less resistant it was for high: the more resistant it was for'high pressures, the less readily it adapted itself t-o checking the low. Thus packing and devices initially insecure were penetrated or blown away before the projectile started; while the energy required to mold the stiffer types, as expanding rings, so as to close minute crevices, approximates 'that necessary to startthe projectile.l and therefore acts only after the escape of uncertain but large volumes of gas.,

Later types of projectile gas-checks rely -more or less entirely upon the pressure of the powder gases for their operation; hence their obstruction is delayed and incomplete., following as itdoes the arrival and passage of gases which, in their initial condition, they are unable to check. Other varieties require some movement of the projectile after discharge before they become effective. These act later, of course, than those depending upon gas pressure to overcome the lesser inertia of movable parts of the device attached to the projectile.

Still other methods employ a series of non-resilient flanges and linterspeysedl packing to obtain a piston or plunger t and action intended to choke the crevices about` the projectile. All of these methods show weakness in the description of their operation. Drawing a series of inelastic flanges in over the gun slopes, while-it unquestionably decreases 'the area of possible leaks, cannot be a positive closure of all of them. There is a minute butl certain lack of uniformity in the loaded position of shell; loading dents scratches, actual erosions, particles of powder residuum, etc.,-all tend to form openings which no inelastic material subject to `casual pressure along |the slopes instead ofat ri ht angles to them, can be expected to In fact, all such methods correspond p closely in their initial action to the use of un valves; there is bound to be considerable leakage before they can be crushed yinto iirm contact and made tight by an overwhelming pressure. These designs are as l a rule complicated, add a prohibitive cost 65 to the projectile, and are ineective, through incipient and'.

ground and ill-fitting automatic. gasrequiring the development of considerable pressure and a certain time interval to overcome the inertia of plungers, change the shape Yof material, as` expanding rings, sleeves or capsules, or force the flow of a material. It needA hardly be po-inted out that a material so soft as to flow before the lower .gas pressures,'is detrimental -in a modern high powered gun; it cannot resist the torsional stress vof the rifling, and is certain to clog the grooves.

Before describing my invention, Ait is well to state that a positive shell gas-check must withstand practically the same pressure as the'breech gas-check. The latter, although mobile when warmed, is subjected to great pressure in closing the breech so as to'be forced into close contact with'the cleanedl 'surface of the gas-'check slopes. Iny this condition, it Vcan hardly be indented by a hammer stroke. f Nevertheless, the slightest mal-adjustment of the device causes it to leak, The packing is cut or torn away before the pressure, and the exposed metal vparts are oxidized in a manner never shown in the chamber itself. This is explained by the-fact j that the first formed gases are super-oxidized and in escaping through ineifectively closed or minute crevices, act with a concentrated blow-pipe effect. The 95v damage is ordinarily confined to the period of lower pressures,-before the inertia of the mushroom-is overcome and it is driven back so as to readjust and enforce closure ofthe check. No comparative, progressive, or step-by-step device of shell gas-check thus far proposed can be expected to withstand such an attack so as to insure protection against erosion. An eiiici'ent gas-check to' prevent erosion must operate successively, even when conditions are unfavorable. However small the avenue of approach may be, yit isimpossible for any easily compressible material to check even the lower pressures. Powder gas is capable of-leakage through all the convolutions of the 'screw thread of. a-base plug though covered by a flange, before the projectile has left its seat." `Moreover, this gas retains sufficient heabto ignite the bursting charge. 'Dhese statements are believed necessary in order to in dicate 'what is required of a positive and complete projectile gas-check as compared with all Vother partial -or step-by-step devices. f

My invention consists of a positive acting projectile gas-check; initiallyv secure '1" gainst high as well as low pressures; unique in that its action, when the shell is properly and vigorously seated in its loaded 125 position, is independentv of the pressure of the powder gases or further movement of the projectile. It is determinedly effective before discharge. The nature and position of the gas-check are such as to cause its 139 v tween the projectile and the bore, molding y material,

compression, in the process of seating, be-

it firmly and solidly into all inequalities of surface so as to prevent leakage. It is car ried along with the projectile out of the gun, functioning throughout the entire passage of the bore. It is so recessed and placed as to avoid masking the rifling or reducing the rotating effect of the band, and is securely held against the side pressure of the powder gases which tend to blow it out of position. Finally, through being composed of tenacious material, loaded with heavy lubricants, in proportions merely sufiicientI to obtain impressionable qualities under high pressure, it incidentally reduces friction between rotating band and rifiing;

closes the minute leaks which form under the shifting ridges of the rotating band, and so prevents the enlargement and eXtensionof fire-cracks in the grooves of the riding.

Having thus described the general nature and purpose of my invention, the details thereof will be understood by reference' to the accompanying drawings, in which the same parts are indicated by the same letters throughout the several views.

Figure l shows diagrammatically that portion of the gun in rear of the riiing, with the shell partly entered in the projectile chamber, the gun body being shown in section and the shell in elevation. Fig. 2 shows a vertical section, on a larger scale, of the parts of the device shown in Fig. 1, with the shell in the position indicated in said figure. Fig. 3 shows a similar section to Fig. 2, except that the shell has been pushed home, and the riding band is engaging the compression slope. F ig.- 4 shows a similar view to Figs.. 2 and 3, but with the anti-erosion device applied to the rear 'end of the rifling band. Fig. 5 shows still another modification, but with'the anti-erosion device applied to the front end of the riiing band, and Fig. 6 is detail, showing the expanding ring .removed from the apparatus.

Referring first to Figs. l, 2, and 3, Arepresents the inner tube of the gun body, provided with the usual gun slope a and the usual'compression slope a. B shows the projectile carrying the band C, commonly known as the rifling band, which by engaging the ritiing imparts rotary motion to the shell. This band is mounted in the dovetailed groove b in the periphery of the shell, in the usual way. This band is recessed at its forward end, as shown in Figs. 2 and 3, and has the overhanging lip c, and the inclined annular face c. D represents a ring, pad, or coil, of packing, which 1s composed of any suitable spun or absorbent referably covered with canvas. The constltuent parts of the packing are preferably boiled in a mixture of tallow, or graphite, or other heavy' lubricant, until, when cold and subjected to heavy pressure, it assumes a substantially, rigid shape, but still impressionable under shock. This ring D of compressible material is held between the inclined faces c and c and the follower ring F, which has inclined faces f and f', engaging the compression rinfr D; and it also has the inclined face f3, adapted to engage the compression slope a, and also the shoulder f2, which engages the abutting face of the groove in the shell, as shown in Fig. 2.

Inside the ring D is a split metal ring E, having wedge-shaped ends e, and split as at c (see Fig. 6). This ring is sprung into place before the rings D and F are applied.

As the shell is rapidly shoved home, the inclined face f3 of the follower ring F will strike the compression slope a', and the momentum of theshellwill cause the various wedging surfaces, including the ring E, to force the eXpansible ring D outward from the position shown in Fig. 2 to the position shown in Fig. 3. At the same time, the shoulder f2 of the ring F will be forced backward, as shown in Fig. 3.

Should the gun already be eroded, the force of arresting the shell will be sufficient to cause the expansible ring D to press out and fit into the eroded grooves, the result being that an effective gas-check will be secured, which will in a large mea sure, if not entirely, prevent the rush of gases forward from the powder chamber past the rifling band.

In the form of device shown in Fig. 4, the follower ring F is mounted in the groove near the rear end of the riling band, and is provided with inclined faces f and ft, in rear of which is mounted the ring D', similar to that already described with reference to Figs. l to 3, and a ring E similar to the ring E already described. After these two rings D and E are'in place, the follower ring H is screwed onto the rear end of the rifling band, and this ring is also provided with inclined surfaces zy and 71,. An additional compression slope a2 is provided in the 115 gun body; and as the shell is shoved homo toward the compression slope, the ring F strikes this slope a2 and compresses the ring D, forcing it outward and forming a tight joint, as before. This form of device is especially suited for guns already eroded, in that the powder chamber may be slightly bored out, leaving the slope a2, as shown in Fig. 4.

Referring now to Fig. 5, a compound follower ring is shown, made of two rings F2 and I, fastened together in any convenient way, as by the rivets K. Moreover, there is an elongated annular groove 00 in the rifling band c, to permit travel backward of the compound 'follower ring. The ring F2 is shown as provided with a shoulder vffto engage a corresponding shoulder on the ring I, andthe latter ring is provided with a shoulder 2, normally engaging the shoulder on the projectile. The rear outer face of the ring I is tapered as at i', to form a continuous wedging Jface with the tapered surface f' of the ring F2. In Fig. 57 the shell is shown as 4nearly home; but when it i-s driven home,

as in the ordinary process of ramming, the

inclined surfaces 2 and yf3 of the compound ring will engage the compression slope a',

wedging the split ring E outward, and at the same time expanding the ring D. For

convenience of assembly, the ring I may also be split, asis Well known in vthe ordnance art.

In any of the forms of the device hereinbefore-l described,fit will be noted that the more or less plastic ring 'D will be pressed out-ward, due to the :energy expended in shoving the shell home, supplemented by the inertia of the shell, and that the band or ring D will be pressed outward, making a Y snug fit, even though there be irregularities in the abutting surface of the inner wall of the bore.

t will be obvious that various modications might be made in the herein described apparatus, and in the construction, combi-nation, and arrangement of parts,wliicli could be used without departingfroin the spirit of my invention., Y Having thus described my invention, what I claim and desire to secure by Letters Patent of the United States is 1. A gas check for projectiles, comprising the ordinary riling band provided with a' 40 recess therein, a split wedging ring mounted in said recess, a semi-plastic band mounted in said recess exterior to said split ring, and a follower ring provided with a wedge- 'shaped rear face adapted to engage said split ring and said semi-plastic band, and wedge the two outward, said follower-ring being adapted to engage a wedge `face in the bore of the Oun, substantially asdescribed. 2. A gas check for irojectiles, comprising the ordinary riding band provided with a recess therein, with an inclined wedge face forming the inner rear wall of said recess, a split wedgingring mounted in said recess, a semi-plasticband mounted in said recess exterior to said split ring, and a follower ring provided with a wedge-shaped rear face adapted to engage said split ring and said semi-plastic band,'and wedge the two outward, said 'follower ring being adapted to engage a wedge :tace in the bore of the gun,

substantially as described.

3. A gas check for projectiles, comprising a rifling band provided with a recess therein, a split wedging rin mounted in said recess, a semi-plastic ban containing lubricating material, mounted iny said recess exterior to said split ring, and a follower ring provided with awedge-shaped rea-r face adapted to engage said split ring and said semi-plastic band, andvwedge the two outward, said ollower ring being adapted to engage a wedge face in the bore of the gun, substantially as described. j

4. A gas check for projectiles, com rising a riing band providedwith a recess t erein, with an 'inclined wedge face forming the inner rear wall of said recess, a split wedging ring mounted, in said recess, a semiplastic band, containing lubricating material, mounted in said recess exterior to said split ring, and a follower ring provided with a wedge-shapedrear tace adapted to engage said splitring and said semi-plastic band, and wedge the two outward, said follower ring being adapted to engage a wedge face in the bore of the gun, substantially as described. v

5. A gas'check for projectiles, comprising a ritling band provided with a. recess therein, and an overhanging lip extending over the g@ rear portion of said recess, a split wedging ring mounted in said recess, a semi-plastic bandmounted in 'said recess exterior to said split ring, and partly beneath said overhanging lip, and a follower ring provided with a rearwardlyl extending overhanging lip engaging the upper anterior face of said semi-plastic band, and. with a wedge-shaped rear face adapted to engage said split 4ring and saidsemi-plastic band, and wedge the two outward, said follower j ring 'being adapted to engage a wedge lface in the bore of the gun, substantially as described.

6. A gas check for projectiles, comprising a ritling band provided with a recess 105 therein, and an overhangin-g lip extending over the rear portion' of said recess, with an inclined wedge face forming the inner rear wall of said recess, a split wedging ring mounted insaid recess, a semi-plastic band 11o mounted in said recess exterior to said 4split ring, and partly beneath said overhanging lip, and a follower ringprovided with a rearwardly extending overhanging lip engaging the upperanteriortace of said semi- M5 plastic band, and with a wedge-shaped rear face adapted to engage said split ringand said semi-plastic band, and wedge `the two outward, said follower ring being adapted to engage a wedge `face in the boreof the ma gun, substantially., as described.

j 7 A gas check for projectiles, com rising a riliing band provided with a recesst erein,

a split wedging ring mounted in said recess,

a semi-plastic band, containing lubricating material2 mounted in said recess exteriork to said split ring, and a follower ring composed of an inner split ring slipped over the projectile, and an outer ring secured thereto, said inner and outer rings being provided with e Wedge-shaped rear face adapted to engage said split ring and lseid semi-plastic band, and Wedge the two outward, and also being adapted t0 engage :1f-Wedge face in the bore of the gun, substantially as described. l

8. A- gas check for projectiles, comprising a rifiing band provided with a recess therein,

with an inclined wedge face forming the inner rear wall of said recess, asplit wedging ringV mounted in said recess, a semiplastic band, containing lubricating material, mounted in said recess 4exterior to saidl split ring, and a follower ringcomposed 15 of an inner split ring slipped over the projectile, and an outer ring secured thereto, said inner and outer rings being provided with a wedge-shaped rear face adapted to engage said split ring and said semi-plastic band, and wedge the two outward, and also being adapted to engage a wedge face in the bore of scribed.,

yIn testimony whereof, I afx my signature, in presence of two witnesses.

the gun, substantially as' de- Witnesses:

HOBNER P. DIBBLE, V SAMUEL A. FAULKNER. 

